The TOC works by picking up text from the document that uses the paragraph styles you include. You mention two styles, but it isn't clear to me if these are paragraph styles to include, or styles to apply to the TOC listings -- these are different tasks.
It seems unlikely that you would be including any sort of body text styles in the TOC to be picked up as listings. More likely you will have some sort of headings with their own paragraph styles that you want to include. So the first thing is to make sure that those things that should appear have a style assigned, and that that style is not used for anything that you DON'T want to appear in the TOC. The next step is to make sure you include that paragraph style, or styles if you've got subheadings, for example, that you also want to include, in the box on the left side. Select the styles from the list in the right-hand box and click the "Add" button between the two boxes to include them in the TOC.
It is also important (essential, in fact) that the TOC be its own story, not threaded into other text. If you try to thread it, it will replace your other text and you'll get nothing but the TOC title. I don't think, from your description, that you tried to put the TOC into an exisiting story, but it's worth the warning.
If your TOC comes back empty, make sure that the "Include Book documents" is checked.